1. Field of the Invention
This invention relates to the production of precise optical components and assemblies, such as laser scanner devices, microphotolithography devices, microscope devices, etc. More particularly, this invention relates to the testing of aberrations present in such systems.
2. Prior Art
It is customary to judge the lens quality on the basis of interferometric evaluation. Although such technique is very sensitive to even minute aberrations in the system, the data interpretation with respect to the value of the particular aberration, such as distortion or astigmatism, is extremely difficult, especially in the case of multicomponent optical assemblies.
A recent use of laser scanning systems for laser printing and semiconductor chip fabrication relies on the optical systems where negative distortions are introduced on purpose. A deviation of the exhibited distortions in the real lens of this kind from the designed one for more than 0.05 microns could be unacceptable for a lens use. Diffraction limited microreduction lenses used on photolithography stage of semiconductor chip manufacturing must have a distortion less than 0.2 microns anywhere in the usable field and minimal amount of aberrations overall. Therefore, it is appreciated that there remains a need for a method which allows quantitative analysis of lens and lens assembly aberrations, particularly distortions in micron and submicron distortion ranges.